title: Stereotactic ablative radiotherapy: a potentially curable approach to early stage multiple primary lung cancer.
abstract: BACKGROUND
  Surgical resection has been the standard treatment for early stage multiple primary lung cancer (MPLC). However, a significant proportion of patients with MPLC cannot undergo surgery. For this report, the authors explored the role of stereotactic ablative radiotherapy (SABR) for patients with MPLC.
  
  
  METHODS
  Patients with MPLC who received SABR (50 grays [Gy] in 4 fractions or 70 Gy in 10 fractions) for the second tumor were reviewed. Four-dimensional, computed tomography-based, planning/volumetric image-guided treatment was used for all patients. Treatment outcomes/toxicities were analyzed.
  
  
  RESULTS
  For the 101 patients who received SABR, at a median follow-up of 36 months and with a median overall survival (OS) of 46 months, the 2-year and 4-year in-field local control rates were 97.4% and 95.7%, respectively. The 2-year and 4-year OS rates were 73.2% and 47.5%, respectively; and the progression-free survival (PFS) rates were 67% and 58%, respectively. Patients who had metachronous tumors had better OS and PFS than patients who had synchronous tumors (2-year OS: 80.6% metachronous vs 61.5% synchronous; 4-year OS: 52.7% vs 39.7%, respectively; P = .047; 2-year PFS: 84.7% vs 49.4%, respectively; 4-year PFS: 75.6% vs 30.4%, respectively; P = .0001). For patients who either underwent surgery or received SABR for an index tumor, the incidence of grade ≥ 3 radiation pneumonitis was 3% (2 of 71 patients); however, this increased to 17% (5 of 30 patients) for those who received conventional radiotherapy for an index tumor. Other grade ≥ 3 toxicities included grade 3 chest wall pain (3 of 101 patients; 3%) and grade 3 skin toxicity (1 of 101 patients; 1%).
  
  
  CONCLUSIONS
  SABR achieves promising long-term tumor control and survival and may be a potential curative treatment for early stage MPLC.
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Joe Y
authors.initials: JY
authors.lastname: Chang
authors.forename: Yung-Hsien
authors.initials: YH
authors.lastname: Liu
authors.forename: Zhengfei
authors.initials: Z
authors.lastname: Zhu
authors.forename: James W
authors.initials: JW
authors.lastname: Welsh
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Gomez
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Komaki
authors.forename: Jack A
authors.initials: JA
authors.lastname: Roth
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Swisher
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000473:pathology / Q000601:surgery*; D011829:Radiation Dosage; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome
keywords: metachronous tumors; multiple primary lung cancer; stereotactic ablative radiotherapy; stereotactic body radiotherapy; synchronous tumors